The invention concerns an X-ray spectrometer for carrying out both an element analysis and a structural analysis of a polycrystalline sample with
a) a polychromatic source for providing an X-ray beam that is incident on the sample,
b) a holding means for holding the sample,
c) one or more fluorescence channels which can select X-ray beams of a special wavelength and energy and have detectors for measuring the selected X-ray beams,
d) at least one diffractometry channel which is configured such that it selects, by means of a monochromator, an X-ray beam wavelength of the source subsequent to diffraction of the X-ray beams by the sample, and has a detector for measuring the selected X-ray beams.
An X-ray multichannel spectrometer of this type is disclosed in U.S. Pat. No. 5,406,608A.
The X-ray multichannel spectrometer described in U.S. Pat. No. 5,406,608A moreover also has a diffractometry channel for X-ray structural analysis, which is operated with parallel beam optics, in addition to the conventional fluorescence channels which measure the emitted X-ray fluorescence radiation that is characteristic for a certain material in each case and from which the presence and, if necessary, the relative amount of certain elements in the measuring sample can be concluded. In the conventional X-ray spectrometer, a first collimator arrangement must initially be placed or inserted between the X-ray source and the sample to be measured in order to use this diffractometry channel for measurements. The diffractometry channel moreover contains a monochromator which can be rotated with respect to the sample and has a second collimator arrangement at its entry, through which the X-ray radiation that is diffracted by the sample at a certain angle is incident on a crystal, where it is also diffracted and is incident on a detector via a third collimator arrangement.
The conventional X-ray multichannel spectrometer is disadvantageous due to high construction expenses and the corresponding susceptibility to disturbances as well as high production costs. The parallel beam optics that is used for the diffraction analysis moreover requires a large amount of space, since the collimators have considerable depth. There must be an adequate amount of space for the first collimator arrangement between the source and the sample. This space also remains during fluorescence measurements, in which the first collimator arrangement is removed from the area between the source and the sample, and therefore causes permanent strong reduction of the beam intensity.
In the conventional X-ray multichannel spectrometer, the entire monochromator is moved in a curved, usually circular, motion about the sample center to perform a diffraction scan. The mechanism that is required for this purpose is also very complex and also requires a great deal of space, maintenance and expense.
In contrast thereto, it is the object of the invention to modify a conventional X-ray multichannel spectrometer of the above-mentioned type with simple technical means in such a fashion that one and the same device enables reliable element analysis and inexpensive X-ray diffraction, wherein the at least three collimator arrangements for the diffractometry channel, which are required according to prior art, are omitted and the diffraction scan can be performed without complex motion mechanism of the monochromator in the diffractometry channel.